Web Technology

History of the Internet Internet was developed by ARPANet in ARPANet (American Research Project Agency Network)

1969 ARPANET was born. 4 nodes were inter-connected: UCLA,SRI,UCSB, U. Charley Kline from UCLA sent 1 st packet.

1970 ARPANET used NCP (Network Control Protocol), first end-to- end protocol

nodes were connected. Ray Tomlinson of BBN invented program.

was chosen by Ray Tomlinson to separate the userid and hostname.

1974 TCP (Transmission Control Protocol) was invented by Vint and Bob.

1975 First mailing list was created by Steve Walker.

1978 TCP splited into TCP and IP.

1982 TCP/IP is used to inter-connect networks. Thus, the Internet!!!

1984 DNS (Domain Name System) was introduced. > 1000 hosts.

1987 > 10,000 hosts.

1989 > 100,000 hosts

1991 WWW was created by Tim Berners-Lee. Linux was released by Linus Torvalds.

1994 NSFNET was transformed to commercial network. Shopping mall. Can order pizza online.

WWW(World Wide Web) www was created by Tim Berners Lee in The www usually referred to as “The Web”. It is a collection of Millions of files stored on thousands of computers (Web Servers) all over the world. These files may be Text Documents, pictures, videos, sounds, programs and interactive Environment.

Gopher Gopher is Application Layer Protocol. Designed for distributing, searching, and retrieving documents over the Internet. This protocol was invented by a team led by Mark P. McCahill. The Gopher protocol was strongly oriented towards a menu-document design. Gopher is presented an alternative to the World Wide Web in its early stages.

Gopher A file-like hierarchical arrangement that would be familiar to users. A simple syntax. A system that can be created quickly and inexpensively. Gopher is designed to function and to appear much like a mountable read-only global Network File System.

Governing Body of Internet No one person, company, organization or government runs the Internet. It is a globally distributed network comprising many voluntarily interconnected autonomous networks. Its governance is conducted by a decentralized and international multi stakeholder network of interconnected autonomous groups drawing from civil society, the private sector, governments, the academic and research communities and national and international organizations.

Protocols for governing the web HTTP SMTP POP3 MIME IMAP FTP TELNET

HTTP(Hyper Text Transfer Protocol) HTTP is a pull protocol, the user pulls information from a remote site. Protocol consists of GET and POST commands to transfer data. HTTP uses cached files to speed up transfers HTTP Uses LAN accessible cache that is Proxy Server. Proxy allows for reduced load on the internet connection

SMTP(Simple Mail Transfer Protocol) The protocol is very simple. SMTP is a push protocol, information is pushed to a remote site. Uses port 25. All files are ascii text.

POP3(Post Office Protocol 3) Post office protocol. Mail access client. Uses port 110. Messages are downloaded to client but can be stored on server. Does not easily allow multiple clients.

IMAP Internet Mail Access Protocol Improved POP3 Automatically assigns folders Leaves mail on server Only transfers as much as needed per message (headers, subject only on list)

MIME(Multipurpose Internet Mail Extensions) Generally it is used for encoding. Handles Non-ASCII data in an ASCII transfer medium. Defines extensions to support binary attachments of arbitrary format – Images, Audio, Video and multi-media messages – Text having unlimited line length or overall length – Multiple objects in a single message – Character sets other than ASCII – Multi-font messages

FTP(File Transfer Protocol) Used to Transfer files between two computers. Goals of FTP Service – Promote sharing of files (programs and/or data) – Encourage indirect/implicit use of remote computers – Shield users from variations in file storage among hosts – Transfer data reliably and efficiently

Problems of File Transfer At first, file transfer may seem simple Heterogeneous systems use different: – Operating Systems – Character Sets – Naming Conventions – Directory Structures – File Structures and Formats FTP need to address and resolve these problems

FTP(File Transfer Protocol) To resolve these problems FTP uses two ports Port 21 for Connection Control. Port 20 for transfer Data.

User Interface User Data Transfer Function User Protocol Interpreter Server Protocol Interpreter Server Data Transfer Function client server Control Connection Data Connection 21 20

TELNET Terminal Networking It is also known as Network Virtual Terminal. TELNET is a protocol that provides – general, – bi-directional, – eight-bit byte oriented communications – Command Line interface